In the field of injection molding, particularly in multi-cavity molds of as many as 128 cavities, there has risen a problem that is heretofore unrecognized. That is, the molding pressure applied from a manifold is multiplied many times by the areas of the probe, runners, gate, and outlets with many of these areas applying force which tends to separate the probe assembly from the mold. On occasion, the separation force exceeds the capacity of the molding apparatus.
Additionally, it has been common practice to design a probe assembly with a large cavity adjacent to the mold gate. When this cavity is filled with molten molding material, the molding material exerts separating pressures which may exceed the holding strength off the molding machine fasteners or locking devices. Even if the molding apparatus is capable of retaining the assembly together, changes in temperature such as cooling after a molding operation can allow molding material to enter a seam line similar to flash in molding and then upon reheating, the material in the seam line acts as a block against precise, tight mold assembly. Repeated temperature cycling inherent in the molding process only aggravates the problem.
Also, proper temperature compensation of probe assemblies has been difficult, if not impossible, to achieve using existing probe designs. The only solution has been to design probes with the front face acting as a reference so that the probe is free to expand and contract in a rearward direction away from the mold and toward the molding material manifold.